Size-reducing mill



Oct. 5, 1943. R. s. BUTLER 2,331

SIZE-REDUCING MILL v Filed Dec. 4. 1939 2 Sheets-Sheet 1 final-WM- Oct. 5, 1943. R. s. BUTLER 2,331,173

SIZE-REDUCING MILL Filed Dec. 4, 1939 2 Sheets-Sheet 2 1510671207: Koberidifiui'ler:

M 14: MM I a ti'm nqy.

Patented Oct. 5, 19 4 1" r SIZE -REDUCIN G MILL Robert S. Butler, Santa Monica, Calif., assignor to Sullivan Machinery Company, a corporation of Massachusetts Application December 4, 1939, Serial No. 307,361

3 Claims.

My invention relates to size-reducing apparatus, and more particularly to improvements in the size-reducing chamber construction of such apparatus.

In my improved size-reducing mill which forms the subject matter of U. S. Letters Patent No. 2,168,082, granted August 1, 1939, there is utilized a longitudinally oscillated size-reduction chamber elongated in its direction of oscillation and at least approximating uniformity of crosssectional area on planes normal to its path of swing, and desirably having discharge orifices in the wall thereof which is most remote from the axis of oscillation of the chamber. In such a chamber there is a subjection of the chamber load or contents not merely to a longitudinal pressure at each change of direction of movement thereof along its path, but also to a transverse reducing pressure intermediate said reversals of movement, said transverse reducing pressure caused in part by the centrifugal action resulting from the rotary oscillation of the chamber and also caused in part by a tangential thrust or pressure caused by the oscillation of a chamber with an arcuate bottom about an axis appropriately related to the chamber. With such a chamber there tends to be a great deal of wear upon the chamber walls, and especially at the-inner surface of the radially outermost (usually bottom) wall of the chamber. There is, therefore, since the wear tends to be the greatest in the central longitudinal zone of the chamber, during a substantial period of use, an alteration in the cross sectional areas on given radial planes,

with maximum increases in cross sectional area adjacent the longitudinal center of the chamber and at points to either side thereof. Otherwise described, it may be said that the wear will at different points depend in considerable degree upon the length of chamber contents which periodically pass over particular points, and the pressure exerted on the surface at such points by the load. It is desirable, however, for maximum efiiciency, that the. general motion of both the reducing media employed and the material undergoing reduction be confined to a. path which conforms generally to the path of the load as a whole, and wandering of the load or freedom of movement should be prevented as far as possible by maintaining the load as a relatively compact mass. This results in its being desirable, so far as practicable, that the cross sectional area at least of the chamber be maintained substantially uniform. The inequality of wear mentioned and the desirability of maintaining uniformity of cross sectional area give rise to some of the problems which it is the object of this invention to solve. 'And the general problem of wear, and

i of economy, give rise to others.

It is an object of'my invention to provide an improved size-reducing mill. It is another object of my invention to provide an improved sizereducing chamber for a size-reducing mill. It is a further object of my invention to provide an improved discharge-orificed wall for a sizereducing chamber. It is still another object of my invention to provide an improved size-reducing chamber construction for a size-reducing mill. It is yet a further object of my invention to provide an improved discharge-orificed-wall element of a size-reducing chamber. Other objects and advantages of my invention will hereinafter more fully appear.

From one aspect my invention comprises the feature of providing a chamber construction in which the wall subjected to maximum wearthe outer wall-is so constructed as to provide for a minimization of deviation from uniformity of chamber cross sectional area during the period between the puttin of the chamber into use and the time when worn parts must be replaced. From another aspect my invention comprises an improved discharge wall construction. From still another aspect the invention comprises an improved chamber wall element. Other aspects will be noted in the description of a preferred embodiment of the invention in this present specification and in the definitions thereof, from it several aspects, in the appended claims.

In the accompanying drawings, in which for purposes of illustration certain illustrative embodiments which the invention may assume in practice have been shown,

Fig. 1 is a view in plan, with the top cover removed and with parts broken away in horizontal section, through a mill in which my invention. in certain of its aspects may be incorporated.

Fig. 2 is an enlarged central longitudinal vertical sectional view through a size-reducing chamber upon the approximate plane of the section line 2-2 of Fig. 1, with parts in elevation.

Fig. 3 is a transverse vertical sectional view on the plane of the line 33 of Fig. 2, through the size-reducing chamber and a portion of the feed. connection of the latter.

Fig. 4 is a detail plan view of a chamber-bottom forming element.

Fig. 5 is a side elevational view (an edgewise view) of the bottom forming element shownin Fig. 4.

6 is a fragmentary transverse sectional view, on an enlarged scale, on the same section plane as Fig. 3, through the bottom portion of a mill chamber.

Fig. 7 is a vertical sectional view with parts in side elevation, on a still larger scale than Fig. 2, upon a plane perpendicular to the axis of chamber swing, showing a modified chamber construction.

Fig. 8 is an enlarged transverse vertical sectional view through the lower part of the chamber of Fig. '7, upon the plane of the line 88 of Fig. 7.

Fig. 9 is a fragmentary side elevational view (an edgewise View) of a bottom forming element.

Fig. 10 is a fragmentary longitudinal, substantially horizontal sectional view, on the plane of the line liil of Fig. 9, and Fi 11 is a Vertical transverse sectional view on the plane of the line I Ii I of Fig. 9, showing details of the structure of a bottom forming element utilizedin the chamber of Fig. 7.

Referring to the drawings, and first to the figures thereof contained in sheet I disclosing the preferred illustrative embodiment of the invention, it will be noted that a frame I provides chambers or compartments 2 and 3 in which there are respectively arranged mill oscillating means generally designated 4 and'a size-reducing chamber providing means generally designated 5, the latter being supported for arcuate oscillation in the compartment 3 about the axis of a shaft 6 which extends through a suitably packed opening I between the chamber 2 and 3. Any suitable driving means may be provided for a shaft 8 which actuates the mill oscillating means 4 and extends out through the wall 9 of the chamber 2. The shaft 6 has rigidly secured thereto, within the chamber 3, a yoke or support member ID to which there is detachably secured, by means of the studs I2 passing through the slotted yoke ends, conical washers I3 engaging conical seats M in the yoke member and nuts i threaded on the studs, a size-reducing chamber structure proper iii of the chamber-providing means 5.

The chamber structure I6 is arcuately elongated and includes herein (a) approximately semi-annular side wall plates ll, l8, (b) an approximately semi-cylindrical top wall i9 having a feed orifice 20 therein adjacent its longitudinal central portion, (0) opposite end walls generally designated-2|, and (d) a built-up bottom wall 22 traversed by discharge orifices 23. One of the side wall plates, herein [8, has an opening 24 therein for removal of the size-reducing medium charge from the chamber when desired, and. this opening is normally closed by a detachable cover plate 25. A flexible conduit 26 communicates with any suitable feed supply not shown, the flexibility of this conduit permitting the necessary oscillation of the chamber without having to provide a pivotal connection in the feed supply line. The top and sides of the chamber are lined with rubber as at 21, suitably bonded directly to the walls or to liner plates for them, direct bonding being practicable upon the top wall as the wear is there the least, and bonding to intermediate liner plates being perhaps preferable in the case of the side walls.

The chamber ends are heavily lined with rubber, as at 28, and are bolted, as at 29, between the side plates and are also connected by through bolts 3|! or studs and nuts 3| to elements 32 and 33 which hold the inner and outer wall elements together and the outer one, 33, of which provides a lip 34 serving to aid in supporting the chamber structure on the yoke I 0.

The side wall plates l1 and 18 extend above and below the top and bottom chamber walls and are connected bytransversely extending bolts 35 which clamp the chamber parts together and pro vide reinforcements for the top wall and sub- Jacent support for the lower wall.

As above indicated, it is desirable that the chamber, which is herein shown as semi-arcuate though it may be of greater or lesser angular extent, be for some purposes uniform in cross section on planes normal to its curvature, and at least, so far as practicable, of approximately uniform cross sectional area on such planes. Since, if the chamber is made initially of a truly semicylindrical curvature, the unevenly concentrated wear will steadily increase the radial dimension of the chamber in its central longitudinal portions, 1. find it desirable to provide a bottom wall whose inner or upper surface conforms to an arc struck from a point more remote than the center of curvature of the inner or upper chamber wall and whose outer surface conforms to an arc struck from a point nearer to it than is the center from which said inner or upper surface is struck, thereby accomplishing two results, to wit, providing a chamber. whose cross sectional area at its central portion is initially less than adjacent its ends but which under wear will have such cross sectional area equalize with that at the chamber ends, and ultimately slightly exceed such last mentioned area, and providing a bottom wall thicker at its center than at its ends and therefore having a capacity better to withstand the greater wear at its central longitudinal portions. It is of course not essential that the discharge wall be bounded by cylindrical surfaces, and the feature of importance with respect to this particular aspect of the invention is that the cross sectional area at the middle (speaking in terms of the length of the chamber) shall be initially slightly less than at the ends; and that the lower chamber wall shall be thicker at its middle than at its ends obviously contributes to economy in material.

Now, with reference to the particular form of bottom wall construction shown in Figs. 2 to 6 inclusive, it will be noted that the bottom wall is made up of several sections, herein for illustrative purposes shown as six in number, and each section extends for the full width of the chamber. The several sections, each of which is designated generally by the numeral 36, are numbered at the center of the chamber 36, at the ends of the chamber 36 and between each end and middle section, 36. Each section is traversed herein by a plurality of series of longitudinally extending discharge slots 31, increasing in discharge area towards the bottom of the section. The slots 31 provide the discharge orifices 23. The several sections 36, 36 and 36 are properly shaped at their ends to provide smooth joints, and the several sections are positioned between the side wall plates l1 and I8 by the fitting of suitable filler plates 38 below the bottoms of the side wallliners. It will be observed that initially the sections are each thinner at their respective ends nearer the ends of the size-reducing chamber and that when ready to be discarded at least the central sections and possibly others will be either nearly uniform in thickness from end to end or even thinner at their ends toward the central point in the length of the chamber.

In the modification of the invention shown in an arc of a circle struck on a radius equal to the radial distance from the axis of chamber swing to the inner surface of the outer wall of the chamber at the extremities of the latter. Each element is plane on one side at 42, and radially ribbed at spaced intervals along the other side thereof as at 43, and between the ribs there are sloping surfaces 44 so arranged that the elements are thicker at their inner sides than at their outer sides, The ribs 43 at their outer surfaces at 45 are parallel to the plane sides of the ele-- ments, and accordingly when a series of elements are assembled side by side, elongated discharge.

slots 46 are formed and these are of increasing width towards their bottoms (outer ends). Each element is provided with a series of openings 41, and, when the elements are in assembled relation, dowel pins 48 extend through the registering openings to locate properly the elements with respect to each other. Otherwise the structure embodiment above described.

- of this modification is similar to the preferred 1 In this form of the invention as well as in the 2 be set in oscillation and feed initiated, that the chamber will fill up to such a point, if the quantity of reducing media is not already adequate continuously to mask the feed opening, until the latter is masked at all times except when the chamber contents are compacted in the chamber ends, and that the material will be gradually reduced in size by the processes of impact and/or attrition, and discharged when small enough to pass through the discharge openings, any suitable means being provided to effect removal of the reduced material from the chamber 3. Feed and chamber load volume will both be automatically controlled and the mill may operate for a long period. By making the discharge wall thicker at its middle portion, and initially closer to the opposite wall at its middle than at its ends, and limiting the reduction in radial chamber dimension at the middle of the chamber to a, practically speaking, harmless degree, and so forming the discharge wall that wear may continue until the radial dimension of the chamber at its middle somewhat exceeds its like dimensions at its ends,

efliciency and long use without shutdowns for chamber replacement can be obtained.

While there are in this application specifically described two forms which the invention may assume in practice, it will'be understood that these forms of the same are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a size-reducing apparatus, a swingable size-reducing chamber curved from end to end and of relatively uniform cross sectional area on 'radial planes substantially from end to end thereof and having a curved inner wall and also orifices, said outer wall curved from end to end and initially formed of maximum thickness at its central portion longitudinally, and with its inner surface disposed to progressively greater degrees, from the ends of said outer wall towards the center thereof, inside an arc concentric with the arc of curvature of the inner chamber wall and including the extremities of the inner surface of said outer wall.

2. For a mill of the character in which a generally arcuate grinding chamber is supported for oscillatory movement and has such movement positively imparted thereto, a grinding chamber having an inlet in the top thereof for material to be ground and having wall elements cooperating to form a generally arcuate grinding space having top and bottom walls initially more closely spaced adjacent their longitudinal central portions than at their ends, and Wholly enclosed except for said inlet and for discharge orifices and approximating uniform cross sectional area normal to its path of oscillation throughout the major portion of its length except as said crosssectional area is deliberately varied by the spacing of said top and bottom walls increasingly from the center towards the ends thereof, certain of said elements providing between them orifices for the discharge of ground material of increasing width toward their outermost boundaries and having means for holding them in fixed relation to each other when assembled.

3. In a size-reducing mill, an oscillatorychamber-providing size-reducing member having an elongated arcuate size-reducing chamber of approximately uniform cross section throughout its length, said chamber having a wall formed of removable sections increasing in thickness from one end toward the other, with thinner sections at the ends and thicker sections adjacent the center and each section arranged with its thinner end towards the chamber end to which such section is closer, whereby said chamber is initially of slightly more restricted cross sectional area at its central longitudinal portions than at its end portions.

ROBERT 8. BUTLER. 

